Retinal malfunction and subsequent photoreceptor cell death result from taurine deficiency in the cat. Studies of the autoradiographic localization of taurine in the retina are proposed here to define the role of taurine in maintaing photoreceptor structure and function. In most types of hereditary pigmentary retinal degenerations, electroretinographic abnormalities are detectable soon after birth and suggest abnormal development of the retina. The proposed research seeks to compare the post-natal development of the retina in the normal miniature French poodle and the miniature French poodle affected with progressive retinal atrophy in order to examine the pathogenetic mechanism in this disease.